The present invention relates to X-ray radiology and more particularly to the attenuation of X-rays by compressing filters to obtain an even X-ray field over the entire scan of the X-ray.
At the present time is is known that when certain portions of the patient are to be X-rayed, those portions may be seen in more detail if they have received a suitable X-ray contrast media. For example, a barium iodine solution may be used as the radiopaque media in the alimentary tract. In an X-ray film dense bone appears white and other materials appear in various shades of gray. However, even with skillful technique, the X-ray picture may be obscured due to unequal attenuation of the X-rays by the patient's own body. Generally, the absorption of the body varies greatly so that the contrast between portions of the body cannot be reproduced within the explosure latitude of the X-ray film. Certain portions of the patient's body are thicker than others and certain portions have bones and organs which differently affect the X-ray picture.
It would be desirable, in order to have an X-ray picture showing the greatest detail of the portion of the patient's body of interest, that the X-ray be evenly attenuated over the entire field (the entire scan) of the X-ray exposure. In one method of attenuation a solid aluminum three-dimensional filter(mask) is formed, see Erdhom & Jacobson, Primary X-Ray Dodging, Radiology 99:694-696, June 1971. The mask (filter) is positioned between the X-ray source and the patient, at the correct proportional distance.